Technical Field
This document discloses a lubrication and cooling system for a machine tool that delivers lubricant entrained in cooled air to the machine tool and/or a work piece.
Description of the Related Art
Industrial operations routinely involve cutting and/or machining of hard materials, such as metals. Such operations often require the application of liquid lubricant and coolant to the machine tool and/or the work piece. Coolants dissipate heat generated by friction between the tool and the work piece, and generally include significant amounts of water. Lubricants, on the other hand, lubricate moving parts of the machine tool, and are normally petroleum-based. Often, a lubricant provides a cooling function and, conversely, a coolant provides a lubrication function. Thus, the terms “coolant” and “lubricant” may interchangeably refer to a “cutting fluid” applied to a work piece that is being machined or cut by a machine tool.
Cutting fluid may be delivered as a continuous stream, which is known as a flood application. Flood application of cutting fluid consumes large quantities of cutting fluid. One consequence of flood application is the need to recover used cutting fluid, filter any scrap particles from the used cutting fluid, and otherwise store and/or recycle the cutting fluid. If the cutting fluid includes a petroleum-based lubricant, any lubricant-coated scrap particles removed from the cutting fluid should be disposed of as hazardous waste. Further, the cutting fluid may itself contain hazardous waste, thereby requiring special handling procedures. A machine shop that employs flood application of cutting fluid may need to store large amounts of cutting fluid on the shop floor, thereby consuming valuable floor space. Further, a machine shop that collects used cutting fluid for recycling and/or for disposal must provide containers for storing the recyclable cutting fluid and/or the disposable cutting fluid, which may also consume valuable floor space. Additionally, if the scrap particles can be recycled, specialized or costly equipment may be required to remove cutting fluid from the metal particles, before the metal particles are fit for recycling.
To avoid the cost and waste associated with flood application of cutting fluid, manufacturers may deliver cutting fluid in the form of small amounts of lubricant entrained in a flow of compressed air, or “shop air,” which provides a cooling function. This technique may include the use of a minimum quantity lubricant (MQL) system that delivers a mist or a atomized form of lubricant in a stream of shop air through a nozzle directed at the work piece. Other MQL systems may deliver a pulsed flow of lubricant in a stream of air. The lubricant may be light, non-petroleum oil delivered under pressure and combined with air in the nozzle before the combined stream is sprayed at the work piece and/or tool. Such systems are also referred to as “near dry” lubricant systems and are frequently used with computer numerical controlled (CNC) machine tools. As an improvement over flood application of cutting fluid, near dry lubricant systems greatly reduce the amount of lubricant used.
However, while near dry lubricant systems are excellent at providing lubrication, they are less effective at providing cooling to the machine tool and/or work piece because the shop air is delivered at the ambient temperature. Due to reduced cooling, use of near dry lubricant systems may result in thermal build-up that results in increased tool-wear, thermal distortion of work pieces and other less than desirable effects. To address this problem, US 2014/0027531 discloses the use of a vortex chamber to cool the shop air before it is directed at the work piece. However, the apparatus disclosed in US 2014/0027531 cannot be easily applied to complex machining operations where a plurality of different machine tools are mounted on a rotating turret because each machine tool typically includes its own nozzle for a more precise application of the lubricant/air flow to the work piece and machine tool.
Accordingly, there is a need for a system that supplies lubricant and cool air to a work piece that is being machined by multiple tools mounted on a rotating turret.